Catalytic isomerization of pentane using ionic liquids

ABSTRACT

Processes for the disproportionation and isomerization of a C 5  hydrocarbon feed using a liquid catalyst comprising an ionic liquid and a halocarbon carbocation promoter are described. The ionic liquid is unsupported, and the reactions occur at temperatures below about 200° C.

BACKGROUND OF THE INVENTION

The Reid vapor pressure (RVP) of gasoline has been utilized by the Environmental Protection Agency as a means of regulating volatile organic compounds emissions by transportation fuels and for controlling the formation of ground level ozone. As these regulations become more stringent and as more ethanol (which has a high vapor pressure) is blended into gasoline, C₅ paraffins need to be removed from the gasoline pool. Moreover, the need to remove components may also extend to some C₆ paraffins. This may result in refiners being oversupplied with C₅ paraffins and possibly C₆ paraffins.

Disproportionation reactions offer a possible solution to this problem. The disproportionation of paraffins (e.g., isopentane (iC₅)) involves reacting two moles of hydrocarbon to form one mole each of two different products, one having a carbon count greater than the starting material and the other having a carbon count less than the starting material, as shown in FIG. 1. The total number of moles in the system remains the same throughout the process, but the products have different carbon counts from the reactants. Additional secondary disproportionation-type reactions can occur in which two hydrocarbons having different carbon numbers react to form two different hydrocarbons having different carbon numbers form those of the feed where the total number of carbons in the products does not change from the total number in the feed (e.g., pentane and octane reacting to form hexane and heptane).

There are a number of different catalysts that have been shown to produce the desired paraffin disproportionation reaction, including zeolites, sulfated zirconias, AlCl₂/SiO₂, ionic solids, platinum on chlorided Al₂O₃/Ga₂O₃ supports, supported ionic liquids, Pt/W/Al₂O₃ and HF/TiF₄. However, these processes have a number of disadvantages. The processes using zeolites, sulfated zirconias, AlCl₂/SiO₂, ionic solids, and platinum on Al₂O₃/Ga₂O₃ supports require elevated temperatures (e.g., 120-450° C.) to carry out the transformation. The HF/TiF₄ system is capable of disproportionation at 51° C., but it utilizes dangerous HF. The supported ionic liquid is active from about 85-125° C. and is composed of the Brønsted acidic trimethylammonium cation. Since the ionic liquid's organic cation is composed of this Brønsted acid, the acid concentration within this catalyst is stoichiometric with respect to the ionic liquid and quite high. Moreover, the supported ionic liquid is deactivated by leaching of the ionic liquid from the support. Additionally, the use of a support increases the cost of the catalyst and may result in a chemical reaction of the support with the acidic ionic liquid over time, as happens when AlCl₃ is immobilized on silica.

Isomerization processes have been used to improve the low octane numbers (RON) of light straight run nathpha. Isomerization processes involve reacting one mole of a hydrocarbon (e.g., normal pentane) to form one mole of an isomer of that specific hydrocarbon (e.g., isopentane), as shown in FIG. 2. The total number of moles remains the same throughout this process, and the product has the same number of carbons as the reactant.

Current isomerization processes use chlorided alumina, sulfated zirconia, or zeolites in conjunction with platinum. Process temperatures range from about 120° C. for chlorided alumina up to about 260° C. for zeolite type catalysts. These reactions are run at temperatures which allow the feed to reach equilibrium. At lower temperatures, the equilibrium favors the branched isomers possessing the higher octane number.

Isomerization processes utilizing ionic liquids have been developed. For example, US 2003/019767 describes an isomerization process for a paraffin hydrocarbon feed using an ionic liquid as a catalyst. The ionic liquid is formed from an N-containing heterocyclic and/or N-containing aliphatic organic cation and an inorganic anion derived from metal halides. The examples show a catalyst:hydrocarbon weight ratio of 1:1 or 1.5:1. The hydrocarbon feeds examined were normal pentane, normal heptane, normal octane, and 3-methylhexane.

US 2004/059173 teaches an isomerization process for linear and/or branched paraffin hydrocarbons. The catalyst comprises an ionic liquid. Over 25 wt. % of a cyclic hydrocarbon additive is included. The ionic liquid is formed from an N-containing heterocyclic and/or N-containing aliphatic organic cation and an inorganic anion derived from metal halides. The ionic liquid:hydrocarbon ratio in the examples is fixed at 1:1 volume ratio. Metal salt additives or Brønsted acids can be included. The feed is a mixture of C₇ hydrocarbons.

U.S. Pat. No. 7,053,261 discusses isomerization of linear and/or branched paraffin hydrocarbons using an ionic liquid catalyst in combination with a metal salt additive. The ionic liquid is formed from an N-containing heterocyclic and/or N-containing aliphatic organic cation and an inorganic anion derived from metal halides. The ionic liquid:hydrocarbon ratio in the examples is fixed at 1:1 volume ratio. The results of the gas chromatograph on the paraffin phase were not reported. The feed is a mixture of C₇ hydrocarbons.

All of these references describe isomerization of the feed; none describes disproportionation reactions. All of the references describe the use of ionic liquids having an acid concentration of at least about 3.0 M. The Brønsted acidic ionic liquid used in US Publication 2003/0109767 was [trimethylammonium][Al₂Cl₇], which has a molar concentration of HCl that ranges from 3.0-4.1 M if the density is in the range of 1.1 to 1.5 g/mL. For US Publications 2004/0059173 and U.S. Pat. No. 7,053,261 the Brønsted acidic ionic liquid used was [trimethylammonium][Al_(1.8)Cl_(6.4)], which has a molar concentration of HCl that ranges from 3.3-4.5 M if the density is in the range of 1.1 to 1.5 g/mL. These estimated densities are within the ranges measured for similar ionic liquids.

None of the references indicate the composition of the product mixture; as a result, it is unclear what was actually formed in the reactions. Assuming that all of the other products were disproportionation products (which is unlikely to be correct as Ibragimov et al. teach that cracking occurs in addition to disproportionation (see below), but it sets an upper limit on the greatest possible conversion, yield, etc. for the disproportionation products). The conversion rates corrected for mass or volume were calculated as follows: using the reported iso-selectivity, the selectivity to other compounds was calculated as (100-iso-selectivity). The % conversion was determined from the reported %-iso yield and % iso-selectivity. The % conversion thus determined was used to determine the reaction rate by the following formula: volume rate=(% conversion/time (h))×(mL HC/mL IL) or as mass rate=(% conversion/time (h))×(g HC/g IL). The % conversion was then used with the computed selectivity to other compounds to set an upper limit on the yield of disproportionation products. The yield of the other compounds and yield of isomers was then calculated using the calculated selectivity to other compounds and the total yield. Since the reaction rate is dependent on the ratio of ionic liquid:hydrocarbon, the rates were corrected according to these ratios.

With respect to US 2003/0109767, the corrected conversion rates for mass were very low. For n-C₅, the corrected conversion rate for mass ranged was between 3.5 and 18.2. For n-C₇, it ranged from 2.6 to 9.3, for n-C₈, it was 3.3, and for 3-methylhexane, it was 4.7. For US 2005/059173, the corrected conversion rates for volume ranged from 0.6 to 47.1 for the C₇ mixture. For U.S. Pat. No. 7,053,261, the corrected conversion rates for volume ranged from 5.4 to 371.3 in the presence of an additional metal salt.

Isomerization is also described in “Isomerization of Light Alkanes Catalysed by Ionic Liquids: An Analysis of Process Parameters,” Ibragimov et al., Theoretical Foundations of Chemical Engineering (2013), 47(1), 66-70. The desired reaction is stated to be isomerization, and the main isomerization products from n-hexane are said to isobutane, isopentane, and hexane isomers. However, isobutane and isopentane are not the isomerization products of n-hexane as isomerization has been defined above. In addition, the article discusses the fact that a significant amount of an undesirable disproportionation reaction begins to occur after about 2-3 hrs. The article indicates that the disproportionation reaction dominates when the ratio of catalyst to hydrocarbon ratio is 2:1, and that cracking and disproportionation dominate at 333K. Because cracking is occurring, the number of moles formed is increased. The optimum isomerization temperature was 303K. The maximum volume rate they obtained was 26 at their high mixing speeds (900 rpm or more) at 0.5 hr.

Some processes involve isomerization and then a cracking reaction in which one mole of a hydrocarbon forms two moles of product, each with a lower carbon number than the starting material. In FIG. 3, the products are illustrated as an alkene and an alkane. Additionally, the total number of moles increases throughout the process.

Alkylation processes involving ionic liquids are also known. In alkylation reactions, one mole of an alkane and one mole of an alkene react to form one mole of an alkane having a carbon number equal to the sum of the carbon numbers of the starting alkane and alkene, as shown in FIG. 4. In an alkylation process, the total number of moles in the system is reduced.

There is a need for improved processes for disproportionation and isomerization of hydrocarbons.

SUMMARY OF THE INVENTION

One aspect of the invention is a hydrocarbon conversion process. In one embodiment, the process includes isomerizing a hydrocarbon feed comprising normal C₅ alkane or branched C₅ alkane by contacting the hydrocarbon feed with a liquid catalyst in a reaction zone under isomerization conditions to form a product mixture comprising at least about 10 wt % branched C₅ alkanes if the hydrocarbon feed was the normal C₅ alkane or at least about 3 wt % normal C₅ alkanes if the hydrocarbon feed was the branched C₅ alkane in 1 hr based on normal C₅ alkane or branched C₅ alkane in the hydrocarbon feed, wherein the liquid catalyst comprises an unsupported ionic liquid and a haloalkane carbocation promoter, and wherein a mass ratio of the ionic liquid to the hydrocarbon feed is less than 0.75:1.

Another aspect of the invention is an isomerization reaction mixture of a hydrocarbon feed comprising a normal C₅ alkane or branched C₅ alkane and a liquid catalyst comprising an unsupported ionic liquid and a haloalkane carbocation promoter, and wherein a mass ratio of the ionic liquid to the hydrocarbon feed is less than 0.75:1, the isomerization reaction mixture comprising at least about 10 wt % branched C₅ alkanes if the hydrocarbon feed was the normal C₅ alkane or at least about 3 wt % normal C₅ alkanes if the hydrocarbon feed was the branched C₅ alkane in 1 hr based on the normal C₅ alkane or branched C₅ alkane in the hydrocarbon feed, the reaction mixture having a Reid vapor pressure in a range of about 1 to about 25 and an octane number in a range of about 50 to about 110.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the disproportionation reaction of iso-pentane.

FIG. 2 illustrates the isomerization reaction of n-pentane.

FIG. 3 illustrates a cracking reaction of n-pentane.

FIG. 4 illustrates an alkylation reaction of isobutane and isobutene.

FIG. 5 is a schematic of one embodiment of the process of present invention.

DETAILED DESCRIPTION OF THE INVENTION

A process for the disproportionation and/or isomerization of a hydrocarbon feed using a liquid catalyst comprising ionic liquids and carbocation promoters is described. The ionic liquids are unsupported and allow the reactions to occur at temperatures below about 200° C.

The disproportionation reaction involves contacting a hydrocarbon feed comprising a C_(n) alkane with a liquid catalyst in a reaction zone to form a product mixture containing C_(n−) alkanes and C_(n+) alkanes, wherein the liquid catalyst comprises an unsupported ionic liquid and a carbocation promoter, and wherein n=5-12.

The isomerization reaction involves contacting the hydrocarbon feed comprising a normal C_(n) alkane (or iso C_(n) alkane) with a liquid catalyst in a reaction zone to form a product mixture containing iso C_(n) alkanes (or normal C_(n) alkanes), wherein the liquid catalyst comprises an unsupported ionic liquid and a carbocation promoter, and wherein n=5-12.

Disproportionation and isomerization occur simultaneously. There is a substantial disproportionation reaction, which can be seen by the fact that significant amounts of C_(n+) and C_(n−) alkanes form. The product mixture can contain at least about 3 wt % C_(n+) alkanes in 1 hr based on the C_(n) alkane fraction in the hydrocarbon feed, or at least 5 wt %, or at least about 7 wt %, or at least about 10%, or at least about 15 wt %, or at least about 20 wt %. There is a corresponding formation of the C_(n−) fraction. There can be at least about 3 wt % C_(n−) alkanes in 1 hr based on the C_(n) alkane fraction in the hydrocarbon feed, or at least 5 wt %, or at least about 7 wt %, or at least about 10%, or at least about 15 wt %, or at least about 20 wt %. The percentages are based on the C_(n) alkane fraction in the hydrocarbon feed.

It is more complex to evaluate the C_(n+) and C_(n−) fractions when the feed comprises more than one C_(n) alkane. When the feed comprises more than one C_(n) alkane, the amount of C_(n+) alkane based on the highest carbon number in the feed can be used. For example if, the feed comprises C₅ and C₆, the amount of C_(n+) can be evaluated using the C₇ fraction. When the feed comprises C₅ and C₈, the increase may be evaluated using the C₉ fraction.

For a feed comprising C₅, at least about 5 wt % each of C⁴⁻ and C₆₊ forms within 30 min, or at least about 10 wt %, or at least about 15 wt %. At least about 10 wt % each of C⁴⁻ and C₆₊ forms within 1 hr, or at least about 15 wt %, or at least about 20 wt %.

For a feed comprising C₇, at least about 3 wt % each of C⁶⁻ and C₈₊ forms within 1 hr, or at least about 5 wt %, or at least about 7 wt %.

Another indication of the existence of the disproportionation reaction is that the number of moles in the product is nearly equal to the number of moles initially present.

There can also be a substantial isomerization reaction, which can be seen by the fact that significant amounts of iso C_(n) alkanes form from normal C_(n) alkanes, and normal C_(n) alkanes form from iso C_(n) alkanes initially. The product mixture can contain at least about 2 wt % normal C_(n) alkanes in 1 hr based on the iso C_(n) fraction in the hydrocarbon feed, or at least about 3 wt %, or at least 4 wt %, or at least about 5 wt %, or at least about 7 wt %, or at least about 10 wt %. The product mixture can contain at least about 5 wt % iso C_(n) alkanes in 1 hr based on the normal C_(n) fraction in the hydrocarbon feed, or at least about 10 wt %, or at least about 15 wt %, or at least about 20 wt %.

For normal C₅ isomerization, at least about 10 wt % of iso C₅ forms within 30 min, or at least about 15 wt %. At least about 15 wt % iso C₅ forms within 1 hr, or at least about 20 wt %.

For iso C₅ isomerization, at least about 2 wt % of normal C₅ forms within 1 hr min, or at least about 3 wt %, or at least about 4 wt %, or at least about 5 wt %.

For normal C₇ isomerization, at least about 5 wt % of iso C₇ forms within 1 hr, or at least about 10 wt %,

The conversion rate for volume can be calculated as volume rate=(% conversion/time (h))×(mL HC/mL IL), where the mL of IL is determined by taking the mass of the ionic liquid and carbocation promoter and dividing by the density of the pure ionic liquid. The conversion rate for volume is at least about 60 in the absence of an added metal salt, or at least about 70, or at least about 80, or at least about 90, or at least about 100, or at least about 120, or at least about 140, or at least about 160, or at least about 180, or at least about 200, or at least about 250, or at least about 300, or at least about 350, or at least about 400, or at least about 450, or at least about 500.

The conversion rate for mass can be calculated as mass rate=(% conversion/time (h))×(g HC/g IL), where the mass of the IL is taken to be the summed mass of the IL and carbocation promoter. The conversion rate for mass in the absence of a metal salt is at least about 20, or at least about 30, or at least about 40, or at least about 50, or at least about 60, or at least about 70, or at least about 80, or at least about 90, or at least about 100, or at least about 110, or at least about 120, or at least about 130, or at least about 140, or at least about 150, or at least about 175, or at least about 200, or at least about 220 or at least about 230, or at least about 240, or at least about 250, or at least about 250.

The present invention provides a method of disproportionating a hydrocarbon feed using less ionic liquid, which is expensive, and obtaining better results at a faster rate. It also provides a method of isomerizing a hydrocarbon feed using less ionic liquid, and obtaining better results at a faster rate.

The hydrocarbon feed can be straight chain paraffins, branched chain paraffins, cycloparaffins, naphthenes, or combinations thereof. The hydrocarbon feed may contain a single C_(n) alkane, such as pentane, or mixtures of two or more alkanes, such as pentane and hexane, or pentane, hexane, and heptane.

In some embodiments, the hydrocarbon feed can be a mixture of 2, 3, 4, 5, or 6 or more consecutive carbon numbers. Typically, there will be one, two, or three carbon numbers that form most of the feed. For example, there could be greater than about 50% of one carbon number, or greater than about 60%, or greater than about 70%, or greater than about 80%. In some embodiments, two or three carbon numbers (or more) could form greater than about 50% of the feed, or greater than about 60%, or greater than about 70%, or greater than about 80%.

In some embodiments, the C_(n) alkane can be substantially pure C_(n) alkane, e.g., greater than about 90% of a C_(n) alkane, such as pentane, or greater than about 95%, or greater than about 97%, or greater than about 98%, or greater than about 99%.

In some embodiments, the C_(n) alkane can be substantially pure normal C_(n) alkane or substantially pure iso C_(n) alkane, e.g., greater than about 90% of a specific normal or iso C_(n) alkane, such as normal pentane, or greater than about 95%, or greater than about 97%, or greater than about 98%, or greater than about 99%.

In other embodiments, mixtures of normal C_(n) alkane and iso C_(n) alkane (both a single C_(n) alkane, such as pentane, and two or more C_(n) alkanes, such as pentane and hexane) are used. The ratio of normal C_(n) alkane to iso C_(n) alkane is typically in the range of about 90:10 to about 10:90, or about 80:20 to about 20:80, or about 70:30 to about 30:70, or about 60:40 to about 40:60, or about 50:50.

As discussed above, the disproportionation reaction of a C_(n) alkane produces C_(n−) and C_(n+) alkanes. For example, the disproportionation of C₅ produces C⁴⁻ and C₆₊ alkanes.

The presence of the C_(n+) fraction distinguishes the disproportionation reaction (FIG. 1) from isomerization reactions which produce isomers of the C_(n) starting material (FIG. 2), or isomerization and cracking which produces isomers of the C_(n) starting material and C_(n−) alkanes due to cracking (FIGS. 2 and 4). The hydrocarbon feed can be dried to remove water before being contacted with the liquid catalyst. The feed can also be treated to remove undesirable reactive compounds such as alkenes, dienes, nitriles, and the like using known treatment processes.

The hydrocarbon feed can be a fluid. The fluid can be a liquid, a vapor, or a mixture of liquid and vapor. When a liquid or liquid-vapor mixture is used, the method is one of the few liquid-liquid disproportionation methods available.

The processes can produce mixtures of alkanes having desirable RVP and RON. The RVP and RON values are calculated on the C₅₊ fraction. The RVP was calculated as the vapor pressure for the system when the vapor:liquid ratio is 4:1 by volume using the Peng Robinson fluid properties model. The RON was calculated with linear volumetric blending, and the RON values used for this calculation were based on the values listed in Phillips 66 Reference Data for Hydrocarbons and Petro-Sulfur Compounds, Bulletin No. 521.

In one embodiment, the product mixture of alkanes has an RVP in the range of about 1 to about 25, or about 8 to about 16, and an RON in a range of about 50 to about 110, or about 60 to about 100. In another embodiment, the product mixture of alkanes has a similar RVP and RON. The octane numbers can be increased by isomerization of the linear paraffins to the corresponding branched compounds.

In some embodiments, the RVP of the product mixture is less than the RVP of the hydrocarbon feed. In some embodiments, the RVP is reduced at least about 5 numbers compared to the hydrocarbon feed, or at least about 7 numbers, or at least about 8 numbers. For example, the RVP for pure (i.e., greater than 99%) normal pentane is 15.6, and the RVP for the product mixture made from substantially pure normal pentane is 13.0 to 13.5. The RVP for pure (i.e., greater than 99%) isopentane is 20.4, and the RVP for the product mixture made from substantially pure isopentane is 12.3 to 12.5.

When the mass ratio of branched alkanes to normal alkanes (i/n) produced from converted pentane feed is in the range of about 6:1 to about 17:1, the selectivity for isoparaffins is in the range of about 70 to about 90%, and when it is in the range of about 7:1 to about 17:1, the selectivity for isoparaffins is in the range of about 80 to about 90%. The high branched to normal ratios for alkanes obtainable with this system are notable, especially in comparison to the methods employing dehydrogenation and metathesis catalysts to effect disproportionation. Generally, when these catalysts are employed, the major isomers formed within the C_(n−) and C_(n+) systems are normal paraffins. The formation of large amounts of normal paraffins is typically not desired due to their low octane numbers.

The formula for calculating the i/n ratio of the product for pure alkanes is (wt. %+iC_(n−)+x wt. % iC_(n)+wt. % iC_(n+))/(wt. % nC_(n−)+y wt. % nC_(n)+wt. % nC_(n+)) with n− greater than or equal to 4, x=1 and y=0 when C_(n)=normal alkane and x=0 and y=1 when C_(n)=isoalkane. For example, for C₅, the calculation would be (wt. % iC₄+x wt. % iC₅+wt. % iC₆+wt. % iC₇+wt. % iC₈)/(wt. % nC₄ ⁺y wt. % nC₅+wt. % nC₆+wt. % nC₇+wt. % nC₈); where x=1 and y=0 when C_(n)=nC₅ and x=0 and y=1 when C_(n) is iC₅). Although C₉₊ alkanes will be present in small amounts, they should not substantially affect the i/n ratio as reported. In addition, the C³⁻ compounds are not included because they don't have normal and iso isomers.

The lower reactivity of normal pentane (nC₅) has made it generally difficult to for the development of a commercial process using nC₅. However, disproportionation of nC₅ at reasonable rates has been demonstrated in more than one embodiment of the present invention.

In order for these reactions to proceed, a stable carbocation likely needs to be present. Carbocations readily undergo skeletal rearrangement at low temperatures. Even at −90° C., rapid rearrangement is observed for degenerate 1,2-methide shifts. Frequently, carbocations are transient intermediates and are short-lived. However, persistent carbocations have been observed in superacidic media.

Ionic liquids offer a number of unique features which make them particularly well suited as reaction mediums for low temperature disproportionation and isomerization. These features include: (1) extremely low volatility, resulting in little to no solvent loss, (2) high chemical diversity, allowing for specific properties to be readily incorporated into the solvent, (3) good thermal stability, (4) readily recyclable, (5) wide liquid ranges, and (6) in some cases (e.g., 1-ethyl-3-methylimidazolium chloroaluminates), they have been shown to be superacidic.

The liquid hydrocarbon feed comprises a C_(n) alkane where n=5-12. A normal alkane is converted to a product mixture comprising iso C_(n) hydrocarbons, normal and iso C_(n−) hydrocarbons and normal and iso C_(n+) hydrocarbons, and an iso alkane is converted to a product mixture comprising normal C_(n) hydrocarbons, normal and iso C_(n−) hydrocarbons and normal and iso C_(n+) hydrocarbons. A blend of normal and iso alkane is converted to a product mixture comprising normal and iso C_(n) hydrocarbons, normal and iso hydrocarbons and normal and iso C_(n+) hydrocarbons, and the highest concentration of C_(n+) hydrocarbons is the C_(n+1) hydrocarbon. For example, for a feed of n-pentane, the product mixture would be isopentane, C⁴⁻ hydrocarbons and C₆₊ hydrocarbons, and for a feed of isopentane, the product mixture would be n-pentane, C⁴⁻ hydrocarbons and C₆₊ hydrocarbons, with the highest concentration being C₆ hydrocarbons for the C_(n+) fractions. A feed comprising a blend of n-pentane and isopentane would produce a product mixture of n-pentane and isopentane, C⁴⁻ hydrocarbons and C₆₊ hydrocarbons. The process is particularly useful for conversion of C₅, C₆, and C₇ alkanes.

The liquid catalyst comprises an ionic liquid and a carbocation promoter. The ionic liquid is in liquid form; unlike prior art processes, it is not supported on an oxide support. In addition, the ionic liquids employed herein do not contain Brønsted acids, so the acid concentration within these systems is less than prior art processes using ionic liquids which are Brønsted acidic organic cations. The acid concentration is less than about 2.5 M, or less than about 2.25 M, Or less than about 2.0 M, or less than about 1.75 M, or less than about 1.5 M.

One or more ionic liquids can be used.

The ionic liquid comprises an organic cation and an anion. Suitable organic cations include, but are not limited to:

where R¹-R²¹ are independently selected from C₁-C₂₀ hydrocarbons, C₁-C₂₀ hydrocarbon derivatives, halogens, and H. Suitable hydrocarbons and hydrocarbon derivatives include saturated and unsaturated hydrocarbons, halogen substituted and partially substituted hydrocarbons and mixtures thereof. C₁-C₈ hydrocarbons are particularly suitable.

The anion can be derived from halides, sulfates, bisulfates, nitrates, sulfonates, fluoroalkanesulfonates, and combinations thereof. The anion is typically derived from metal and nonmetal halides, such as metal and nonmetal chlorides, bromides, iodides, fluorides, or combinations thereof. Combinations of halides include, but are not limited to, mixtures of two or more metal or nonmetal halides (e.g., AlCl₄ ⁻ and BF₄ ⁻), and mixtures of two or more halides with a single metal or nonmetal (e.g., AlCl₃Br). In some embodiments, the metal is aluminum, with the mole fraction of aluminum ranging from 0<Al<0.25 in the anion. Suitable anions include, but are not limited to, AlCl₄ ⁻, Al₂Cl₇ ⁻, Al₃Cl₁₀ ⁻, AlCl₃Br⁻, Al₂Cl₆Br⁻, Al₃O₉Br⁻, AlBr₄ ⁻, Al₂Br₇ ⁻, Al₃Br₁₀ ⁻, GaCl₄ ⁻, Ga₂Cl₇ ⁻, Ga₃Cl₁₀ ⁻, GaCl₃Br⁻, Ga₂Cl₆Br⁻, Ga₃Cl₉Br⁻, CuCl₂ ⁻, Cu₂Cl₃ ⁻, Cu₃Cl₄ ⁻, ZnCl₃ ⁻, FeCl₃ ⁻, FeCl₄ ⁻, Fe₃Cl₇ ⁻, PF₆ ⁻, and BF₄ ⁻.

The ionic liquid is combined with one or more carbocation promoters. In some embodiments, the carbocation promoter is added to the ionic liquid. In other embodiments, the carbocation promoter is generated in situ. However, in situ production might not provide reproducible results.

Suitable carbocation promoters include, but are not limited to, halo-alkanes, mineral acids alone or combined with alkenes, and combinations thereof. Suitable halo-alkanes include but are not limited to 2-chloro-2-methylpropane, 2-chloropropane, 2-chlorobutane, 2-chloro-2-methylbutane, 2-chloropentane, 1-chlorohexane, 3-chloro-3-methylpentane, or combinations thereof. In some embodiments, the carbocation promoters are not cyclic alkanes.

Suitable mineral acids include, but are not limited to, HCl, HBr, H₂SO₄, and HNO₃. Although HF can also be used, it is less desirable due to safety issues. If the mineral acid is not strong enough to protonate off a hydrogen from a C—H bond, isobutene or another alkene can be added with the mineral acid to produce the desired carbocation promoter. The mineral acid can be generated in situ by the addition of a compound that reacts with the ionic liquid. In situ acid generation can also occur as a result of reaction with water present in the system. The mineral acid may also be present as an impurity in the ionic liquid.

2-chloropropane, and 2-chlorobutane were used successfully as carbocation promoters. HCl was generated in situ by the addition of methanol to the ionic liquid, resulting in the partial degradation of the Al₂Cl₇ ⁻ anion with concomitant formation of HCl. This method was sufficient to catalyze the disproportionation.

The molar ratio of the carbocation promoter to the ionic liquid in the liquid catalyst is typically in the range of about 0:1 to about 3:1, or about 0.1:1 to about 1:1. This relates to forming the carbocation promoter from the halo-alkane or mineral acid. This ratio is important relative to the specific type of anion. For example, if the anion is AlCl₄ ⁻, a reaction is unlikely to occur or will be poor because the aluminum is fully coordinated. However, if the anion is Al₂Cl₇ ⁻, there is some aluminum present that can coordinate to the carbocation promoter's anion, assisting in generating the carbocation from the carbocation promoter.

The mass or volume ratios of liquid catalyst (ionic liquid and carbocation promoter) to hydrocarbon feed are less than 1:1. This is desirable because the ionic liquid is an expensive component in the process. In some embodiments, the mass ratio of ionic liquid to hydrocarbon feed is not more than about 0.75:1, or not more than about 0.7:1, or not more than about 0.65:1, or not more than about 0.60:1, or not more than about 0.55:1, or not more than about 0.50:1. In some embodiments, the volume ratio of ionic liquid to hydrocarbon feed is not more than about 0.8:1, or not more than about 0.7:1, or not more than about 0.6:1, or not more than about 0.5:1, or not more than about 0.45:1, or not more than about 0.4:1, or not more than about 0.35:1, or not more than about 0.3:1, or not more than about 0.25:1.

The liquid hydrocarbon feed is contacted with the liquid catalyst at temperatures of about 200° C. or less, or about 175° C. or less, or about 150° C. or less, or about 125° C. or less, or about 100° C. or less, or about 90° C. or less, or about 80° C. or less, or about 70° C. or less, or about 60° C. or less, or in the range of about 0° C. to about 200° C., or about 0° C. to about 175° C., or about 0° C. to about 150° C., or about 10° C. to about 150° C., or about 25° C. to about 150° C., or about 30° C. to about 150° C., or about 40° C. to about 150° C., or about 50° C. to about 150° C., or about 55° C. to about 150° C.

The pressure in the reaction zone is typically in the range of about 0 MPa to about 8.1 MPa. The pressure should be sufficient to ensure that the hydrocarbon feed is in a liquid state. Small amounts of vapor may also be present, but this should be minimized.

The reaction typically takes places in the presence of a gas. Suitable gases include, but are not limited to nitrogen, hydrogen, argon, helium, hydrogen chloride and the like.

The residence time in the reaction zone is generally less than about 10 hr, or less than 7 hr, or less than 5 hr, or less than 4 hr, or less than 3 hr, or less than 2 hr, or less than 1 hr. The reaction time and conversion are based on the time needed to reach equilibrium of the initial reaction products, such as 2-methylpentane and isobutane from the disproportionation of isopentane. The reaction time is a function of the degree of mixing, the reaction temperature, the concentration of the carbocation promoter, the molar ratio of the carbocation promoter to ionic liquid, and the mass/volume ratio of ionic liquid to hydrocarbon being reacted. Generally, increasing any of these conditions will increase the reaction rate. Under some conditions, greater than 90% conversion is possible.

The % selectivity for the disproportionation reaction is defined as: [(sum of the wt. % C_(n−) and C_(n+) compounds)/(100-wt. % C_(n) feed)]×100. The % selectivity for the disproportionation reaction is typically at least about 40%, or at least about 45%, or at least about 50%, or at least about 55%, or at least about 60%, or at least about 65%, or at least about 70%, or at least about 75%, or at least about 80%, or at least about 85%, or at least about 90%, or at least about 94%.

For blends, the selectivity for the disproportionation reaction would be similar as above. For example, for a blend consisting of 50% isopentane and 50% n-pentane, the % selectivity for the disproportionation reaction is defined as: [(sum of the wt. % C⁴⁻ and C₆₊ compounds)/(100-wt. % feed)]×100, where the C_(n) feed is taken to be the summed wt. % of isopentane and n-pentane. A simple equation similar to this may not be adequate for more complex blends.

The % selectivity for the isomerization reaction to isoparaffins (S_(iso-isom)) is defined as (z(wt. % isoparaffin C_(n)))/(100-wt. % C_(n) feed)×100, where z=0 when the C_(n) feed is isoparaffin and z=1 when the C_(n) feed is n-paraffin. The % selectivity for isoparaffin disproportionation is defined as (wt. % isoparaffins of C_(n−)+wt. % isoparaffins C_(n+))/(100-wt. % C_(n) feed)×100 (S_(iso-disp)). The % selectivity for isoparaffins is defined as (wt. % isoparaffins of C_(n−)+wt. % isoparaffins C_(n+)+z(wt. % isoparaffin C_(n)))/(100-wt. % C_(n) feed)×100, where z=0 when the C_(n) feed is isoparaffin and z=1 when the C_(n) feed is n-paraffin (S_(isoparaffin)); or S_(isoparaffin)=S_(iso-isom)+S_(iso-disp). The selectivity for isoparaffins is typically at least about 40%, or at least about 45%, or at least about 50%, or at least about 55%, or at least about 60%, or at least about 65%, or at least about 70%, or at least about 75%, or at least about 80%, or at least about 85%, or at least about 90%.

For blends, the selectivity for isoparaffins would be similar as above. For example, for a blend consisting of 50% isopentane and 50% n-pentane, the % selectivity for the isoparaffins reaction is defined as: [(sum of the wt. % iC₄ and iC₆₊ compounds)/(100-wt. % C_(n) feed)]×100, where the C_(n) feed is taken to be the summed wt. % of isopentane and n-pentane. A simple equation similar to this may not be adequate for more complex blends.

The selectivity is highly dependent on the type of feed used. For example, for iC₅, the selectivity for the disproportionation reaction typically can be in the range of about 92-94%. However, the selectivity for the disproportionation reaction for nC₅ is much lower, e.g., in the range of about 67-76% because a substantial amount of isomerization to isopentane occurs.

Conversion for the disproportionation and isomerization reactions is defined as 100-wt. % C_(n) feed. The conversion is typically at least about 50%, or at least about 55%, or at least about 60%, or at least about 65%, or at least about 70%, or at least about 75%, or at least about 80%, or at least about 85%, or at least about 90%.

For blends, the conversion would be the same as above. For example, for a blend consisting of 50% isopentane and 50% n-pentane, the % conversion is equal to 100-wt. % C_(n) feed, where the C_(n) feed taken to be the summed wt. % of isopentane and n-pentane.

For example, with an iC₅ feed, initially the products are primarily the isoparaffins of the C₄ and C₆ compounds along with some nC₅. Because iC₅ is more thermodynamically preferred, the amount of nC₅ that forms is relatively small, and the dominating pathway is disproportionation. Since the kinetic products are isoparaffins, the selectivity for isoparaffins can be similar to disproportionation. However, the mixture is not completely at equilibrium, so as the product continues to react, some of the initially formed isoparaffins of the disproportionation products begin to convert to their corresponding n-paraffins. As this occurs, the selectivity for isoparaffins decreases, but the selectivity for disproportionation does not.

With a feed of nC₅, the initial products are again primarily the isoparaffins of the C₄ and C₆ compounds and iC₅. Because nC₅ is thermodynamically disfavored, the amount of iC₅ that forms is substantially greater relative to the formation of nC5 from the iC5 feed. In this case, significant amounts of nC₅ are converted to iC₅. Since the initial products are isoparaffins, the selectivity for isoparaffins remains high. However, since a significant portion of nC₅ is converted to iC₅, the selectivity for disproportionation is less than it was when iC₅ is used. As the reaction progresses, iC₅ and nC₅ continue to disproportionate and the selectivity for disproportionation increases during the reaction. Conversely, the selectivity for isoparaffins decreases as the mixture equilibrates because the initially formed isoparaffin disproportionation products convert to their normal isomers.

At higher temperatures, the relative concentration of normal paraffins increases, which ultimately results in decreased selectivities for isoparaffins relative to lower temperatures.

Although the reaction will proceed simply by contacting the hydrocarbon feed and the liquid catalyst, the reaction rate is generally too slow to be commercially viable. The reaction rate can be substantially increased by increasing the stirring speed of the reaction. This indicates that under some conditions the rate of reaction is mass transfer limited and is not reflective of the true elementary steps of the reaction. In addition to simply stirring the reaction mixture, a baffle can be included in the reactor to aid in obtaining good mixing. The baffle helps to prevent a vortex from forming in the reactor. The formation of a vortex would reduce the amount of mixing even in the presence of stirring.

One embodiment of the process 100 is a continuous-flow reactor as shown in FIG. 5. Feed 105, including the liquid hydrocarbon and carbocation promoter (if present), passes over a drying bed 110 and is continuously introduced to the reactor 115 while simultaneously withdrawing product 120. The liquid catalyst (or ionic liquid alone) 112 is introduced to the reactor 115. The carbocation promoter can be added with the hydrocarbon feed, or with the ionic liquid, or both. The reactor desirably includes a stirrer 160 to mix the hydrocarbon feed 105 and the liquid catalyst. The gaseous products 150 can be separated in the reactor 115. The effluent 120 is sent to a settler 125, where the heavier ionic liquid phase separates as a bottom layer 130. The used ionic liquid stream 165 can be recycled to the reactor 115 and/or the regenerator 135. The upper hydrocarbon layer phase 140 is removed from the settler 125, yielding the liquid product 145. The gaseous products 170 are separated in settler 125. These gaseous products 170 can be combined with gaseous products 150 which could then be used as feed in alkylation units (not shown). The used ionic liquid 165 can be regenerated in regenerator 135 to remove deactivated liquid catalyst so it can be reused. Fresh ionic liquid 155 can be added to the regenerated ionic liquid stream 175 as needed and sent to the reactor 115. Fresh ionic liquid can also be added to the regenerator 135, as needed.

The ionic liquid can be regenerated in a variety of ways. The ionic liquid containing the deactivating polymer could be contacted with a reducing metal (e.g., Al), an inert hydrocarbon (e.g., hexane), and hydrogen and heated to about 100° C. The deactivating polymer will be transferred to the hydrocarbon phase, allowing for the conjunct polymer to be removed from the ionic liquid phase. See e.g., U.S. Pat. No. 7,651,970; U.S. Pat. No. 7,825,055; U.S. Pat. No. 7,956,002; US 2007/0142213; US 2007/0249486, each of which is incorporated herein by reference. Another method involves contacting the ionic liquid containing the deactivating polymer with a reducing metal (e.g., Al) in the presence of an inert hydrocarbon (e.g. hexane) and heating to about 100° C. The deactivating polymer will be transferred to the hydrocarbon phase, allowing for the conjunct polymer to be removed from the ionic liquid phase. See e.g., U.S. Pat. No. 7,674,739 B2; US 2007/0249485 A1; US 2010/0147740 A1, each of which is incorporated herein by reference. Still another method of regenerating the ionic liquid involves contacting the ionic liquid containing the deactivating polymer with a reducing metal (e.g., Al), HCl, and an inert hydrocarbon (e.g. hexane), and heating to about 100° C. The deactivating polymer will be transferred to the hydrocarbon phase, allowing for the CP to be removed from the IL phase. See e.g., US 2007/0142217, which is incorporated herein by reference. The ionic liquid can be regenerated by adding a homogeneous metal hydrogenation catalyst (e.g., (PPh₃)₃RhCl) to the ionic liquid containing the deactivating polymer and an inert hydrocarbon (e.g. hexane). Hydrogen would be introduced, and the deactivating polymer would be reduced and transferred to the hydrocarbon layer. See e.g., US 2007/0142218, which is incorporated herein by reference. Another method for regenerating the ionic liquid involves adding HCl, isobutane, and an inert hydrocarbon to the ionic liquid containing the deactivating polymer and heating to about 100° C. The deactivating polymer would react to form an uncharged complex, which would transfer to the hydrocarbon phase. See e.g., US 2007/0142216, which is incorporated herein by reference. The ionic liquid could also be regenerated by adding a supported metal hydrogenation catalyst (e.g. Pd/C) to the ionic liquid containing the deactivating polymer and an inert hydrocarbon (e.g. hexane). Hydrogen would be introduced and the deactivating polymer would be reduced and transferred to the hydrocarbon layer. See e.g., US 2007/0142215, which is incorporated herein by reference. Still another method involves adding a suitable substrate (e.g. pyridine) to the ionic liquid containing the deactivating polymer. After a period of time, an inert hydrocarbon would be added to wash away the liberated deactivating polymer. The ionic liquid precursor [1-butyl-1-methylpyrrolidinium][Cl] would be added to the ionic liquid (e.g. [1-butyl-1-methylpyrrolidinium][Al2Cl7]) containing the deactivating polymer followed by an inert hydrocarbon. After a given time of mixing, the hydrocarbon layer would be separated, resulting in a regenerated ionic liquid. See, e.g., US 2007/0142211, which is incorporated herein by reference. Another method involves adding the ionic liquid containing the deactivating polymer to a suitable substrate (e.g. pyridine) and an electrochemical cell containing two aluminum electrodes and an inert hydrocarbon. A voltage would be applied and the current measured to determine the extent of reduction. After a given time, the inert hydrocarbon would be separated, resulting in a regenerated ionic liquid. See, e.g., US 2010/0130804, which is incorporated herein by reference.

The contacting step may be practiced in laboratory scale experiments through full scale commercial operations. The process may be operated in batch, continuous, or semi-continuous mode. The contacting step can take place in various ways, with both concurrent and co-current flow processes being suitable. The order of addition of the reactants is not critical. For example, the reactants can be added individually, or some reactants may be combined or mixed before being combined or mixed with other reactants.

Disproportionation of nC₅ and iC₅ has also been achieved at temperatures as low as 45° C. The reaction was faster with iC₅ than with nC₅. Gas chromatograph (GC) analysis revealed that the primary compounds formed were isoparaffins using the analytical method ASTM UOP690-99; very few C³⁻ hydrocarbons formed. The products of the reaction for n-C₅ were broadly divided into the following categories: C³⁻, n-C₄, iC₄, iC₅, C₆ paraffins (C₆P) and C₇₊ hydrocarbons. The products of the reaction for iso C₅ were broadly divided into the following categories: C³⁻, n-C₄, iC₄, nC₅, C₆ paraffins (C₆P) and C₇₊ hydrocarbons. The selectivity to these products was constant over a wide range of isopentane conversions. However, at higher conversions, the selectivity to C₆ paraffins decreased, while the selectivity to iC₄ and C₇₊ hydrocarbons increased, which is likely the result of secondary disproportionation-type reactions. An analysis of both the headspace and the liquid phase revealed that C³⁻ hydrocarbons form in small amounts.

In some places, demand for iC₄ exceeds supply, and disproportionation could help alleviate this problem.

For iso-pentane conversion, the selectivity to the various products (product selectivity being defined as [wt. % compound/(100-wt. % C_(n) feed)]*100) was nearly constant up to about 52% conversion at 55° C. Higher isopentane conversions resulted in decreased selectivity to C₆ paraffins and higher selectivities to iC₄ and C₇₊ hydrocarbons, which was likely the result of secondary disproportionation-type reactions.

With iso-pentane conversion, the extent of isomerization to n-pentane was minimal, but observable, because the reactant was already present in the more thermodynamically favored state. It was consistently observed that the selectivity for isomerization of isopentane to n-pentane centered around 7%, regardless of the % conversion of isopentane.

A significant stir rate dependence on the reaction rate was observed. Under the conditions used, the benefits of increased mixing began to taper off at stir rates greater than 700 rpm, which indicates that much of the kinetics of the reaction below 700 rpm is mass transfer limited.

The other products that form during the disproportionation reaction of isopentane were mainly isobutane and C₆₊ isoparaffins. The selectivity to these products was also nearly constant with isopentane conversion. However, at higher conversions, the selectivity to the C₆ paraffins decreased, while there was a concomitant increase in selectivity for isobutane and C₇₊ isoparaffins. It is important to note that very little C³⁻ formed in the reactions at 55° C. as revealed by a headspace analysis and by the analytical method ASTM UOP980-07.

Under similar conditions (e.g., volume of ionic liquid, temperature, stir rate, etc.), the rate of nC₅ conversion is dependent on the type of ionic liquid used, as the same reaction proceeds at a much greater conversion rate in [1-butyl-1-methylpyrrolidinium] [Al₂Cl₇] than in [tributyl(hexyl)phosphonium] [Al₂Cl₆Br] ([(^(n)Bu)₃P(Hex)][Al₂Cl₆Br]). Despite the increase in reactivity, the selectivities for the products were similar to what was observed with the ionic liquid [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br].

Isomerization and disproportionation of n-hexane has been found to occur at temperatures as low as 45° C. in several different ionic liquids (e.g., [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], [1-butyl-1-methylpyrrolidinium][Al₂Cl₇], 1-butyl-3-methylimidazolium][Al₂Cl₇] and trihexyl(tetradecyl)phosphonium heptachloroaluminate ([(n-Hex)₃P(tetradecyl)][Al₂Cl₇])). The promoter used in all of these reactions, except for [1-butyl-3-methylimidazolium][Al₂Cl₇], was 2-chloro-2-methylpropane, which served to generate the active tert-butyl cation. Trace amounts of water or HCl present in [1-butyl-3-methylimidazolium][Al₂Cl₇] was sufficient for the catalysis to occur. A wide range of compounds were formed, including naphthenes, n-paraffins, isoparaffins and even some aromatic complexes, but the major products are paraffins.

Increasing the concentration of 2-chloro-2-methylpropane increased the conversion, and the yield for the higher and lighter molecular weight complexes. The major light components formed were identified by headspace analysis as iC₄, iC₅, 2-methylpentane and unreacted nC₆. However, it did little to change the selectivity for isomerization. Similarly, increasing the reaction time, temperature, and ratio of mass of ionic liquid to mass of hydrocarbon feed increased the overall conversion. It is desirable to minimize the amount of ionic liquid used due to the cost and potential increase in the amount of feed processed per unit ionic liquid.

EXAMPLES Example 1 Experimental Set Up

The set-up included a 300 mL autoclave equipped with a mechanical stirrer, pressure gauge, thermocouple, dipleg, rupture disc and valves to introduce the feed and withdraw an aliquot for GC analysis. The rupture disc vented to a knock out pot. The house nitrogen passed through a pressure regulator to a high surface sodium column and was then split: feeding to the charger for feed introduction or to a line for various uses (i.e., 2-methyl-2-chloropropane/C₅P introduction). The dipleg was constructed such that the height positions it in the paraffin layer. Upon opening the valve, the withdrawn paraffin layer passed through a column of silica, to the GC valve and then through a metering valve into a waste container. The reaction mixture was analyzed using the ASTM UOP690-99 method. The S_(isoparaffin) was calculated by summing the wt. % contribution of the C4-C8 isoparaffins that are separable using the ASTM UOP690-99 method, but does not include the contributions from the C9+ fraction. Consequently, these values represent lower limits for the selectivity. Similarly, the S_(iso-disp) were determined using this analytical method and is also a lower limit. The RVP was calculated on the C₅₊ fraction as the vapor pressure for the system when the vapor:liquid ratio is 4:1 by volume using the Peng Robinson fluid properties model. The RON was calculated on the C₅₊ fraction with linear volumetric blending and the RON values used for this calculation were based on the values listed in Phillips 66 Reference Data for Hydrocarbons and Petro-Sulfur Compounds, Bulletin No. 521.

Example 2 Synthesis of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br]

An oven-dried round bottom flask was charged with [(^(n)Bu)₃P(Hex)][Br]. The material was attached to a rotary evaporator and dried under vacuum at 110° C. for at least 14 h. The dried [(^(n)Bu)₃P(Hex)][Br] was immediately brought into a nitrogen glovebox and stored there. A synthesis was achieved by massing 17.589 g (47.88 mmol) of [(^(n)Bu)₃P(Hex)][Br] into an oven-dried flask equipped with a stir bar in the nitrogen glovebox. To this was added 12.775 g (95.81 mmol) of AlCl₃ at ambient temperature. The mixture was stirred and the solids slowly reacted over the course of one week to produce a homogenous pale-yellow liquid.

Example 3 Synthesis of [1-butyl-1-methylpyrrolidinium][Al₂Cl₇]

An oven-dried round bottom flask was charged with [1-butyl-1-methylpyrrolidinium][Cl]. The material was attached to a rotary evaporator, dried under vacuum at 110° C. for at least 14 h, and then sealed under vacuum with a connecting adapter. The dried [1-butyl-1-methylpyrrolidinium][Cl] was immediately brought into a nitrogen glovebox and stored there. A synthesis was achieved by massing 57.14 g (322 mmol) of [1-butyl-1-methylpyrrolidinium][Cl] into an oven-dried flask equipped with a stir bar in the nitrogen glovebox. To this was added 83.93 g (629 mmol) of AlCl₃ at ambient temperature and the mixture stirred. The solids reacted to produce a homogenous liquid.

Example 4 Synthesis of with [1-butyl-3-methylimidazolium][Al₂Cl₇]

An oven-dried round bottom flask was charged with 1-butyl-3-methylimidazolium chloride. The material was attached to a rotary evaporator, dried under vacuum at 110° C. for at least 14 h and then sealed under vacuum with a connecting adapter. Afterwards, the dried 1-butyl-3-methylimidazolium chloride was stored in a nitrogen glovebox. A synthesis was achieved by massing 50.04 g (286 mmol) of 1-butyl-3-methylimidazolium chloride into an oven-dried flask equipped with a stir bar in the nitrogen glovebox. To this was added 76.40 g (573 mmol) of AlCl₃ at ambient temperature, and the mixture stirred. The solids react to produce a homogenous liquid.

Example 5 iC₅—Stir Rate Effect at 350 rpm with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br]

A 300 mL stainless steel autoclave, stainless steel baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.39 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], and the autoclave head was attached. To the sample cylinder, 1.451 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 119 g of iso-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The iso-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 18 g of iso-pentane using the same method described above and attached to the autoclave. The autoclave was heated to 55° C., and the 2-chloro-2-methylpropane/iso-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 145 psi (1 MPa), and the autoclave was then set to stir at 350 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to iso-pentane was 0.38 and the volume ratio was 0.19. The mass rate of reaction was 38, and the volume rate was 75 after 1.4 h. The results of the run are shown in Tables 1 and 2.

TABLE 1 Disproportionation and Isomerization of iso-Pentane at 55° C., 350 rpm, wt. % of reaction mixture t % S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) 1.4 20 0.00 7.20 0.02 80.46 1.31 6.84 4.13 11.2 93 82 2.7 28 0.01 10.38 0.04 72.48 2.04 9.93 5.09 9.94 92 84 4.4 36 0.01 13.64 0.07 64.29 2.70 12.75 6.54 9.48 92 85

TABLE 2 Time (h) 1.4 2.7 4.4 NA Wt. % feed C3P 0.00 0.01 0.01 0.00 C4P 7.22 10.43 13.71 0.00 C5P 81.77 74.53 66.99 99.86 C6P 6.84 9.94 12.74 0.00 C7P 1.67 2.47 3.32 0.00 C8P 0.52 0.73 1.00 0.00 C9+ 1.56 1.51 1.80 0.00 C5N 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 C7N 0.01 0.00 0.00 0.00 C8N 0.34 0.34 0.38 0.00 C6A 0.00 0.00 0.00 0.00 C7A 0.00 0.00 0.00 0.00 C8A 0.05 0.05 0.05 0.00 nC4-nC5 0.00 0.00 0.00 0.14 unknowns mmoles (based on wt. %) C3P 0 0 0 0 C4P 124 179 236 0 C5P 1133 1033 928 1384 C6P 79 115 148 0 C7P 17 25 33 0 C8P 5 6 9 0 C9+ 12 12 14 0 C5N 0 0 0 0 C6N 0 0 0 0 C7N 0 0 0 0 C8N 3 3 3 0 C6A 0 0 0 0 C7A 0 0 0 0 C8A 0 0 1 0 nC4-nC5 0 0 0 2 unknowns Total mmoles 1374 1374 1372 1386

Example 6 iC5—Stir Rate Effect at 700 rpm with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br]

A 300 mL stainless steel autoclave, stainless steel baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.352 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], and the autoclave head was attached. To the sample cylinder, 1.453 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 112 g of iso-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The iso-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 15 g of iso-pentane using the same method described above and attached to the autoclave. The autoclave was heated to 55° C., and the 2-chloro-2-methylpropane/iso-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 115 psi (0.793 MPa), and the autoclave was then set to stir at 700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to iso-pentane was 0.40 and the volume ratio was 0.20. The mass rate of reaction was 47, and the volume rate was 93 after 1.5 h. The results of the run are shown in Tables 3 and 4.

TABLE 3 Disproportionation and Isomerization of iso-Pentane at 55° C., 700 rpm, wt. % of reaction mixture t % S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) 1.5 28 0.02 10.35 0.04 72.07 1.94 9.83 5.74 10.5 93 83 2.7 39 0.02 14.84 0.10 61.22 2.82 13.35 7.65 9.5 93 84 4.4 52 0.03 20.18 0.18 47.98 3.66 16.71 11.25 9.1 93 84

TABLE 4 Time (h) 1.5 2.7 4.4 NA Wt. % feed C3P 0.02 0.02 0.03 0.00 C4P 10.39 14.93 20.35 0.00 C5P 74.02 64.05 51.64 99.86 C6P 9.83 13.34 16.71 0.00 C7P 2.55 3.79 5.53 0.00 C8P 0.82 1.25 1.99 0.00 C9+ 1.99 2.17 3.13 0.00 C5N 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 C7N 0.00 0.01 0.01 0.00 C8N 0.33 0.37 0.51 0.00 C6A 0.00 0.00 0.00 0.00 C7A 0.00 0.00 0.01 0.00 C8A 0.06 0.06 0.09 0.00 nC4-nC5 0.00 0.00 0.00 0.14 unknowns mmoles (based on wt. %) C3P 0 0 1 0 C4P 179 257 350 0 C5P 1026 888 716 1384 C6P 114 155 194 0 C7P 25 38 55 0 C8P 7 11 17 0 C9+ 16 17 24 0 C5N 0 0 0 0 C6N 0 0 0 0 C7N 0 0 0 0 C8N 3 3 5 0 C6A 0 0 0 0 C7A 0 0 0 0 C8A 1 1 1 0 nC4-nC5 0 0 0 2 unknowns Total mmoles 1371 1370 1363 1386

Example 7 iC5—Stir Rate Effect at 1700 rpm with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br]

A 300 mL stainless steel autoclave, stainless steel baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.398 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], and the autoclave head was attached. To the sample cylinder 1.453 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 106 g of iso-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The iso-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 23 g of iso-pentane using the same method described above and attached to the autoclave. The autoclave was heated to 55° C., and the 2-chloro-2-methylpropane/iso-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 139 psi (0.958 MPa), and the autoclave was set to stir at 1700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to iso-pentane was 0.40 and the volume ratio was 0.20. The mass rate of reaction was 41, and the volume rate was 82 after 2.5 h. The results of the run are shown in Tables 5 and 6.

TABLE 5 Disproportionation and Isomerization of iso-Pentane at 55° C., 1700 rpm, wt. % of reaction mixture t % S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) 2.5 41 0.01 15.70 0.13 58.64 2.94 14.48 8.09 9.6 93 84 3.7 49 0.02 19.55 0.19 50.66 3.51 16.73 9.34 9.3 93 85

TABLE 6 Time (h) 2.5 3.7 NA Wt. % feed C3P 0.01 0.02 0.00 C4P 15.83 19.74 0.00 C5P 61.58 54.17 99.86 C6P 14.48 16.73 0.00 C7P 4.06 4.97 0.00 C8P 1.31 1.59 0.00 C9+ 2.30 2.33 0.00 C5N 0.00 0.00 0.00 C6N 0.00 0.00 0.00 C7N 0.01 0.00 0.00 C8N 0.36 0.39 0.00 C6A 0.00 0.00 0.00 C7A 0.00 0.01 0.00 C8A 0.06 0.07 0.00 nC4-nC5 0.00 0.00 0.14 unknowns mmoles (based on wt. %) C3P 0 0 0 C4P 272 340 0 C5P 854 751 1384 C6P 168 194 0 C7P 41 50 0 C8P 11 14 0 C9+ 18 18 0 C5N 0 0 0 C6N 0 0 0 C7N 0 0 0 C8N 3 3 0 C6A 0 0 0 C7A 0 0 0 C8A 1 1 0 nC4-nC5 0 0 2 unknowns Total mmoles 1368 1371 1386

Example 8 iC5—Stir Rate at 700 rpm with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br] in Hastelloy C Autoclave at 55° C.

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.416 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], and the autoclave head was attached. To the sample cylinder 1.422 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 114 g of iso-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The iso-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 16 g of iso-pentane using the same method described above and attached to the autoclave. The autoclave was heated to 55° C., and the 2-chloro-2-methylpropane/iso-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 140 psi (0.965 MPa), and the autoclave was set to stir at 700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to iso-pentane was 0.40 and the volume ratio was 0.20. The mass rate of reaction was 70, and the volume rate was 140 after 0.5 h. The results of the run are shown in Tables 7 and 8.

TABLE 7 Disproportionation and Isomerization of iso-Pentane at 55° C., 700 rpm, Hastelloy C autoclave, wt. % of reaction mixture t % S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) 0.5 14 0.00 5.04 0.01 85.85 0.94 4.98 3.16 11.4 93 82 2.8 38 0.14 14.04 0.11 62.48 3.13 12.89 7.08 8.1 92 83 4.5 54 0.03 20.70 0.25 46.32 4.41 16.82 11.45 7.6 92 82

TABLE 8 Time (h) 0.5 2.8 4.5 NA Wt. % feed C3P 0.00 0.14 0.03 0.00 C4P 5.05 14.16 20.94 0.00 C5P 86.79 65.61 50.73 99.86 C6P 4.99 12.88 16.83 0.00 C7P 1.19 3.60 5.73 0.00 C8P 0.38 1.15 2.05 0.00 C9+ 1.30 2.07 3.08 0.00 C5N 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 C7N 0.00 0.01 0.01 0.00 C8N 0.25 0.33 0.50 0.00 C6A 0.00 0.00 0.00 0.00 C7A 0.00 0.00 0.01 0.00 C8A 0.02 0.03 0.05 0.00 nC4-nC5 0.00 0.00 0.00 0.14 unknowns mmoles (based on wt. %) C3P 0 3 1 0 C4P 87 244 360 0 C5P 1203 909 703 1384 C6P 58 150 195 0 C7P 12 36 57 0 C8P 3 10 18 0 C9+ 10 16 24 0 C5N 0 0 0 0 C6N 0 0 0 0 C7N 0 0 0 0 C8N 2 3 4 0 C6A 0 0 0 0 C7A 0 0 0 0 C8A 0 0 1 0 nC4-nC5 0 0 0 2 unknowns Total mmoles 1375 1371 1364 1386

Example 9 iC5—Stir Rate at 700 rpm with [1-Butyl-1-methylimidazolium][Al₂Cl₇] at 55° C. in a Hastelloy C Autoclave

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 55.310 g of [1-butyl-1-methylimidazolium][Al₂Cl₇], and the autoclave head was attached. To the sample cylinder 2.311 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 111 g of iso-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The iso-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 28 g of iso-pentane using the same method described above and attached to the autoclave. The autoclave was heated to 55° C., and the 2-chloro-2-methylpropane/iso-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 150 psi (1.034 MPa), and the autoclave was set to stir at 700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to iso-pentane was 0.41 and the volume ratio was 0.20. The mass rate of reaction was 150, and the volume rate was 310 after 0.6 h. The results of the run are shown in Tables 9 and 10.

TABLE 9 Disproportionation and Isomerization of iso-Pentane at 55° C., 700 rpm, with [1-butyl-3-methylimidazolium][Al₂Cl₇] in a Hastelloy C autoclave, wt. % of reaction mixture t % S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) 0.6 37 0.01 13.86 0.08 62.83 3.11 11.50 8.59 8.2 92 80 1.7 69 0.04 27.55 0.56 31.04 5.47 18.18 17.15 6.9 92 80 2.9 75 0.07 31.33 1.10 24.52 5.47 18.13 19.38 6.6 93 79 4.5 76 0.09 32.31 1.56 23.41 5.34 18.37 18.90 6.4 93 80

TABLE 10 Time (h) 0.6 1.7 2.9 4.5 NA Wt. % feed C3P 0.01 0.04 0.07 0.09 0.00 C4P 13.95 28.12 32.44 33.88 0.00 C5P 65.94 36.51 29.98 28.75 99.86 C6P 11.50 18.17 18.12 18.38 0.00 C7P 3.68 7.80 8.61 8.65 0.00 C8P 1.37 3.36 4.18 4.25 0.00 C9+ 3.01 5.09 5.43 5.09 0.00 C5N 0.00 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 0.00 C7N 0.01 0.01 0.01 0.01 0.00 C8N 0.45 0.84 0.93 0.86 0.00 C6A 0.00 0.00 0.00 0.00 0.00 C7A 0.00 0.03 0.04 0.04 0.00 C8A 0.08 0.06 0.23 0.06 0.00 nC4-nC5 0.00 0.00 0.00 0.00 0.14 unknowns mmoles (based on wt. %) C3P 0 1 2 2 0 C4P 240 484 558 583 0 C5P 914 506 416 398 1384 C6P 133 211 210 213 0 C7P 37 78 86 86 0 C8P 12 29 37 37 0 C9+ 23 40 42 40 0 C5N 0 0 0 0 0 C6N 0 0 0 0 0 C7N 0 0 0 0 0 C8N 4 7 8 8 0 C6A 0 0 0 0 0 C7A 0 0 0 0 0 C8A 1 1 2 1 0 nC4-nC5 0 0 0 0 2 unknowns Total mmoles 1365 1357 1361 1368 1386

Example 10 iC5 [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br] in Hastelloy C Autoclave at 95° C.

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.419 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], and the autoclave head was attached. To the sample cylinder 3.680 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 102 g of iso-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The iso-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 15 g of iso-pentane using the same method described above and then attached to the autoclave. The autoclave was heated to 95° C., and the 2-chloro-2-methylpropane/iso-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 165 psi (1.138 MPa), and the autoclave was set to stir at 1700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to iso-pentane was 0.46 and the volume ratio was 0.23. The mass rate of reaction was 260, and the volume rate was 520 after 0.6 h. The results of the run are shown in Tables 11 and 12.

TABLE 11 Disproportionation and Isomerization of iso-Pentane at 95° C., wt. % of reaction mixture t % S. RVP (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) RON (psi) 0.6 72 0.37 27.78 1.72 28.32 4.2 16.21 21.36 6.3 94 73 80.0 12.5 1.8 76 0.82 31.73 3.91 23.66 5.4 17.15 17.29 4.6 93 76 77.6 12.3 3.1 77 1.05 31.50 5.12 23.14 5.71 17.1 16.38 4.0 92 74 ND ND 4.6 77 1.21 31.56 6.14 22.79 5.90 16.91 15.42 3.7 92 73 ND ND

TABLE 12 Time (h) 0.6 1.8 3.1 4.6 NA Wt. % feed C3P 0.37 0.82 1.05 1.21 0.00 C4P 29.50 35.64 36.62 37.70 0.00 C5P 32.51 29.06 28.85 28.69 99.86 C6P 16.22 17.16 17.10 16.91 0.00 C7P 7.66 8.19 7.96 7.56 0.00 C8P 3.42 3.88 3.79 3.57 0.00 C9+ 9.74 4.63 4.04 3.81 0.00 C5N 0.00 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 0.00 C7N 0.01 0.02 0.02 0.02 0.00 C8N 0.51 0.56 0.53 0.48 0.00 C6A 0.00 0.00 0.00 0.00 0.00 C7A 0.04 0.04 0.04 0.03 0.00 C8A 0.01 0.02 0.02 0.02 0.00 nC4-nC5 0.00 0.00 0.00 0.00 0.14 unknowns mmoles (based on wt. %) C3P 8 19 24 27 0 C4P 508 613 630 649 0 C5P 451 403 400 398 1384 C6P 188 199 198 196 0 C7P 76 82 79 75 0 C8P 30 34 33 31 0 C9+ 76 36 31 30 0 C5N 0 0 0 0 0 C6N 0 0 0 0 0 C7N 0 0 0 0 0 C8N 5 5 5 4 0 C6A 0 0 0 0 0 C7A 0 0 0 0 0 C8A 0 0 0 0 0 nC4-nC5 0 0 0 0 2 unknowns Total mmoles 1343 1391 1402 1411 1386

Example 11 nC5 with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br] at 95° C. in a Hastelloy C Autoclave

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.409 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], and the autoclave head was attached. To the sample cylinder 3.679 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 102 g of n-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The n-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 15 g of n-pentane using the same method described above and then attached to the autoclave. The autoclave was heated to 95° C., and the 2-chloro-2-methylpropane/n-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 160 psi (1.103 MPa), and the autoclave was then set to stir at 1700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to n-pentane was 0.46 and the volume ratio was 0.24. The mass rate of reaction was 130, and the volume rate was 240 after 1 h. The results of the run are shown in Tables 13 and 14.

TABLE 13 Disproportionation and Isomerization of n-Pentane at 95° C., wt. % of reaction mixture t % S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) S_(iso-isom) 1.0 59 0.42 18.63 1.71 19.46 41.34 10.27 8.14 16.9 67 90 33 2.2 70 0.94 22.7 3.08 20.83 29.43 12.54 10.30 12.1 70 87 30 3.5 76 0.91 25.1 4.06 21.56 23.72 13.57 11.03 10.4 72 86 28 4.8 80 1.05 26.39 4.78 21.83 20.06 14.26 11.63 9.4 73 86 27 8.0 85 1.35 27.64 6.10 21.68 14.82 14.78 12.84 8.0 74 83 25

TABLE 14 Time (h) 1.0 2.2 3.5 4.8 8.0 NA Wt. % feed C3P 0.42 0.94 0.91 1.05 1.35 0.00 C4P 20.35 25.78 29.16 31.17 33.74 0.00 C5P 60.81 50.26 45.28 41.90 36.50 99.60 C6P 10.27 12.55 13.59 14.25 14.78 0.00 C7P 4.17 5.17 5.67 5.96 6.24 0.00 C8P 1.63 2.11 2.40 2.57 2.82 0.00 C9+ 2.02 2.71 2.58 2.67 4.10 0.00 C5N 0.00 0.00 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 0.00 0.00 C7N 0.01 0.02 0.02 0.02 0.02 0.00 C8N 0.26 0.32 0.36 0.38 0.41 0.00 C6A 0.00 0.00 0.00 0.00 0.00 0.00 C7A 0.01 0.02 0.02 0.02 0.02 0.00 C8A 0.06 0.13 0.03 0.03 0.04 0.00 nC4-nC5 0.00 0.00 0.00 0.00 0.00 0.34 unknowns nC5-nC6 0.00 0.00 0.00 0.00 0.00 0.05 unknowns mmoles (based on wt. %) C3P 10 21 21 24 31 0 C4P 350 444 502 536 580 0 C5P 843 697 628 581 506 1380 C6P 119 146 158 165 172 0 C7P 42 52 57 59 62 0 C8P 14 18 21 23 25 0 C9+ 16 21 20 21 32 0 C5N 0 0 0 0 0 0 C6N 0 0 0 0 0 0 C7N 0 0 0 0 0 0 C8N 2 3 3 3 4 0 C6A 0 0 0 0 0 0 C7A 0 0 0 0 0 0 C8A 1 1 0 0 0 0 nC4-nC5 0 0 0 0 0 5 unknowns nC5-nC6 0 0 0 0 0 1 unknowns Total 1396 1403 1409 1413 1412 1386 mmoles

Example 12 nC5 with [1-butyl-1-methylpyrrolidinium][Al₂Cl₇] at 95° C.

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 75 mL stainless steel sample cylinder were dried in a 120° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 52.795 g of [1-butyl-1-methylpyrrolidinium][Al₂Cl₇] and the autoclave head was attached. To the sample cylinder 5.24 g of 2-chloro-2-methylpropane, which had previously been dried over activated sieves, was added. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was charged with 98 g of n-pentane from a pressurized feed charger without displacing the nitrogen present in the autoclave. The n-pentane passed over a high surface sodium column to remove any water before entering the autoclave. Similarly, the nitrogen used to pressurize the charger and for all other work passed over a separate high surface sodium column. The sample cylinder was charged with 33 g of n-pentane using the same method described above and attached to the autoclave. The autoclave was heated to 95° C., and the 2-chloro-2-methylpropane/n-pentane solution in the sample cylinder was added with an over-pressure of nitrogen. After complete addition, the initial pressure in the autoclave was 260 psi (1.793 MPa), and the autoclave was set to stir at 1700 rpm. The reaction was monitored periodically by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to n-pentane was 0.44 and the volume ratio was 0.21. The mass rate of reaction was 220, and the volume rate was 450 after 0.6 h. The results of the run are shown in Tables 15 and 16.

TABLE 15 Disproportionation and Isomerization of n-Pentane at 95° C. with [1-butyl- 1-methylpyrrolidinium][Al₂Cl₇], wt. % of reaction mixture t % S. RVP (h) Conv. C3− iC4 nC4 iC5 nC5 C6P C7+ i/n Disp. S_(isoparaffin) S_(iso-isom) RON (psi) 0.6 57 0.49 18.16 2.44 18.55 42.87 10.02 7.48 13.0 68 89 32 ND ND 1.9 84 1.22 28.59 5.73 22.01 15.60 14.75 12.00 8.7 74 85 26 76.1 13.5 3.2 89 1.70 30.42 7.70 21.66 10.57 15.38 12.54 7.1 76 83 24 77.1 13.2 4.4 91 1.96 30.79 8.72 21.31 9.06 15.51 12.65 6.5 76 81 23 77.4 13.0

TABLE 16 Time (h) 0.6 1.9 3.2 4.4 NA Wt. % feed C3P 0.49 1.22 1.70 1.96 0.00 C4P 20.60 34.32 38.12 39.51 0.00 C5P 61.41 37.61 32.23 30.37 99.60 C6P 10.02 14.76 15.39 15.50 0.00 C7P 3.93 6.04 6.24 6.25 0.00 C8P 1.52 2.64 2.85 2.89 0.00 C9+ 1.71 2.97 3.00 3.05 0.00 C5N 0.00 0.00 0.00 0.00 0.00 C6N 0.00 0.00 0.00 0.00 0.00 C7N 0.01 0.01 0.02 0.02 0.00 C8N 0.25 0.39 0.41 0.41 0.00 C6A 0.00 0.00 0.00 0.00 0.00 C7A 0.01 0.02 0.02 0.02 0.00 C8A 0.04 0.01 0.02 0.02 0.00 nC4-nC5 0.00 0.00 0.00 0.00 0.34 unknowns nC5-nC6 0.00 0.00 0.00 0.00 0.05 unknowns mmoles (based on wt. %) C3P 11 28 39 44 0 C4P 354 591 656 680 0 C5P 851 521 447 421 1380 C6P 116 171 179 180 0 C7P 39 60 62 62 0 C8P 13 23 25 25 0 C9+ 13 23 23 24 0 C5N 0 0 0 0 0 C6N 0 0 0 0 0 C7N 0 0 0 0 0 C8N 2 4 4 4 0 C6A 0 0 0 0 0 C7A 0 0 0 0 0 C8A 0 0 0 0 0 nC4-nC5 0 0 0 0 5 unknowns nC5-nC6 0 0 0 0 1 unknowns Total 1402 1421 1435 1441 1386 mmoles

Example 13

nC7—Stir Rate at 1700 rpm with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br] at 55° C.-80° C. in a Hastelloy C Autoclave

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 75 mL stainless steel sample cylinder were dried in a 110° C. oven for at least 8 h. The dried autoclave and sample cylinder were brought into a nitrogen glovebox and allowed to cool to ambient temperature. The autoclave was charged with 50.425 g of [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br], 201 mL of n-heptane (pre-dried by storing over activated 3A MS for several days) and then the autoclave head was attached. The sample cylinder was charged with 8.833 g of a 82.29 wt. % n-heptane and 17.71 wt. % 2-chloro-2-methylpropane mixture, both of which had previously been dried over activated sieves. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was heated to 55° C., and then the 2-chloro-2-methylpropane/n-heptane solution in the sample cylinder was added with an over-pressure of nitrogen. The nitrogen used to provide this overpressure was passed over a high surface sodium column. After complete addition, the initial pressure in the autoclave was 340 psi (2.34 MPa), and the autoclave was set to stir at 1700 rpm. The reaction was monitored by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. After about 24 the temperature was increased to 80° C. At the end of the reaction (45 h), an aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and into a sample cylinder. The sample cylinder was then charged to about 300 psi using nitrogen prior to offline analysis. The mass ratio of ionic liquid to n-heptane was 0.36 and the volume ratio was 0.20. The mass rate of reaction was 2, and the volume rate was 3 after 45 h. The results of the run are shown in Table 17 and were determined using the UOP980 method offline.

TABLE 17 Disproportionation and Isomerization of n-heptane at 55-80° C., 1700 rpm, with [(^(n)Bu)₃P(Hex)][Al₂Cl₆Br] in a Hastelloy C autoclave, wt. % of reaction mixture S. t % S. Isom. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P nC7 C7P C8P Heavies i/n Disp. C7P 0.0 NA 0.00 0.00 0.00 0.04 0.00 0.00 99.25 99.55 0.00 NA NA NA (feed) 45 26 0.07 3.90 0.14 3.31 0.16 2.89 73.44 15.14

Example 14 nC7—Stir Rate at 1700 rpm with [1-Butyl-1-methylimidazolium][Al₂Cl₇] at 95° C. in a Hastelloy C Autoclave

A 300 mL Hastelloy C autoclave, Hastelloy C baffle, and 50 mL stainless steel sample cylinder were dried in a 110° C. oven for at least 5 h and then placed in a glovebox antechamber and evacuated over night. The autoclave and sample cylinder were then brought into a nitrogen glovebox. The autoclave was charged with 55.335 g of [1-butyl-1-methylimidazolium][Al₂Cl₇], 211 mL of n-heptane (pre-dried by storing over activated 3A MS for at least 1 week) and then the autoclave head was attached. The sample cylinder was charged with 15.358 g of a 62.30 wt. % n-heptane and 37.70 wt. % 2-chloro-2-methylpropane mixture, both of which had previously been dried over activated sieves. The sample cylinder was closed under nitrogen, and both the autoclave and sample cylinder were removed from the glovebox. The autoclave was heated to 95° C., and then the 2-chloro-2-methylpropane/n-heptane solution in the sample cylinder was added with an over-pressure of nitrogen. The nitrogen used to provide this overpressure was passed over a high surface sodium column. After complete addition, the initial pressure in the autoclave was 280 psi (1.93 MPa), and the autoclave was set to stir at 1700 rpm. The reaction was monitored by GC. In order to analyze the paraffinic layer, the stirring was stopped, and the product was allowed to settle for 5 minutes. An aliquot was sampled directly from the autoclave by opening a valve from the autoclave, passing the paraffinic layer through a SiO₂ column, and then passing it directly into a GC sample loop. The mass ratio of ionic liquid to n-heptane was 0.40 and the volume ratio was 0.21. The mass rate of reaction was 110, and the volume rate was 210 after 1 h. The results of the run are shown in Tables 18 and 19 and were determined using the UOP690 method. Alternatively, the aliquot could be introduced to a sample cylinder, after passing through the SiO₂ column, and analyzed offline. If this method was used, after introduction of the sample to the sample cylinder, the cylinder would then be charged to about 300 psi using nitrogen prior to offline analysis and analyzed using the UOP980 method.

TABLE 18 Disproportionation and Isomerization of n-heptane at 95° C., 1700 rpm, with [1- butyl-3-methylimidazolium][Al₂Cl₇] in a Hastelloy C autoclave, wt. % of reaction mixture t % nC8- S. (h) Conv. C3− iC4 nC4 iC5 nC5 C6P nC7 C7P C8P nC10 C10+ i/n Disp. S_(iso-isom) 0.0 NA 0.00 0.00 0.00 0.04 0.00 0.00 99.25 99.55 0.00 NA NA NA (feed) 1.0 44 0.58 7.63 0.89 7.58 0.77 7.06 66.21 3.26 3.07 2.43 15 77 22

TABLE 19 Time (h) 1.0 NA Wt. % Feed C3P 0.58 0.00 C4P 8.52 0.00 C5P 8.35 0.04 C6P 7.06 0.00 C7P 66.21 99.55 C8P 3.26 0.00 C9P 1.62 0.00 C10P 1.40 0.00 C10+ 2.43 0.00 C5N 0.00 0.00 C6N 0.00 0.01 C7N 0.03 0.40 C8N 0.40 0.00 C6A 0.00 0.00 C7A 0.06 0.00 C8A 0.04 0.00 nC4-nC5 0.00 nC5-nC6 0.00 0.00 unknowns mmoles (based on wt. %) C3P 13 0 C4P 147 0 C5P 116 1 C6P 82 0 C7P 661 993 C8P 29 0 C9P 13 0 C10P 10 0 C10+ 16 0 C5N 0 0 C6N 0 0 C7N 0 4 C8N 4 0 C6A 0 0 C7A 1 0 C8A 0 0 nC4-nC5 0 nC5-nC6 0 0 unknowns Total 1090 998 mmoles

While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims. 

1. A hydrocarbon conversion process comprising: isomerizing a hydrocarbon feed comprising normal C₅ alkane or branched C₅ alkane by contacting the hydrocarbon feed with a liquid catalyst in a reaction zone under isomerization conditions to form a product mixture comprising at least about 10 wt % branched C₅ alkanes if the hydrocarbon feed was the normal C₅ alkane or at least about 3 wt % normal C₅ alkanes if the hydrocarbon feed was the branched C₅ alkane in 1 hr based on normal C₅ alkane or branched C₅ alkane in the hydrocarbon feed, wherein the liquid catalyst comprises an unsupported ionic liquid and a carbocation promoter comprising a haloalkane, and wherein a mass ratio of the ionic liquid to the hydrocarbon feed is less than 0.75:1.
 2. The process of claim 1 wherein the ionic liquid comprises an organic cation and an anion.
 3. The process of claim 2 wherein the organic cation is selected from the group consisting of:

where R¹-R²¹ are independently selected from C₁-C₂₀ hydrocarbons, C₁-C₂₀ hydrocarbon derivatives, halogens, and H.
 4. The process of claim 2 wherein the anion is derived from halides, sulfates, bisulfates, nitrates, sulfonates, fluoroalkanesulfonates, or combinations thereof.
 5. The process of claim 2 wherein the anion is selected from the group consisting of AlCl₄ ⁻, Al₂Cl₇ ⁻, Al₃Cl₁₀ ⁻, AlCl₃Br⁻, Al₂Cl₆Br⁻, Al₃Cl₉Br⁻, AlBr₄ ⁻, Al₂Br₇ ⁻, Al₃Br₁₀ ⁻, GaCl₄ ⁻, Ga₂Cl₇ ⁻, Ga₃Cl₁₀ ⁻, GaCl₃Br⁻, Ga₂Cl₆Br⁻, Ga₃Cl₉Br⁻, CuCl₂ ⁻, Cu₂Cl₃ ⁻, Cu₃Cl₄ ⁻, ZnCl₃ ⁻, FeCl₃ ⁻, FeCl₄ ⁻, Fe₃Cl₇ ⁻, PF₆ ⁻, and BF₄ ⁻.
 6. The process of claim 1 wherein the carbocation promoter further comprises a mineral acid.
 7. The process of claim 1 further comprising stirring the hydrocarbon feed and the liquid catalyst while contacting the hydrocarbon feed with the liquid catalyst.
 8. The process of claim 1 wherein the haloalkane comprises 2-chloro-2-methylpropane, 2-chloropropane, 2-chlorobutane, 2-chloro-2-methylbutane, 2-chloropentane, 1-chlorohexane, 3-chloro-3-methylpentane, or combinations thereof.
 9. The process of claim 1 wherein a molar ratio of the carbocation promoter to ionic liquid is in a range of about 0:1 to about 3:1.
 10. The process of claim 1 wherein a residence time in the reaction zone is about 10 hr or less.
 11. The process of claim 1 further comprising separating the ionic liquid from the product mixture.
 12. The process of claim 11 further comprising regenerating the separated ionic liquid.
 13. The process of claim 1 further comprising: drying the hydrocarbon feed before contacting the hydrocarbon feed with the liquid catalyst; or treating the hydrocarbon feed to remove one or more of alkenes, dienes, or nitriles; or both.
 14. The process of claim 1 wherein a conversion rate for volume is at least about 60 in the absence of an added metal salt.
 15. The process of claim 1 wherein a concentration of acid in the ionic liquid is less than 2.5 M.
 16. The process of claim 1 wherein the product mixture comprises at least about 15 wt % branched C₅ alkanes when the hydrocarbon feed was the normal C₅ alkane in 1 hr based on the normal C₅ alkane in the hydrocarbon feed.
 17. The process of claim 1 wherein a selectivity for isoparaffins is at least about 70%, and a conversion is at least about 40%.
 18. The process of claim 1 further comprising disproportionating the hydrocarbon feed concurrently with isomerizing the hydrocarbon feed.
 19. The process of claim 1 wherein the hydrocarbon feed comprises a mixture of C₅ alkanes and at least one of C₄ alkanes or C₆ alkanes, or both.
 20. An isomerization reaction mixture of a hydrocarbon feed comprising a normal C₅ alkane or branched C₅ alkane and a liquid catalyst comprising an unsupported ionic liquid and a carbocation promoter comprising a haloalkane, and wherein a mass ratio of the ionic liquid to the hydrocarbon feed is less than 0.75:1, the isomerization reaction mixture comprising at least about 10 wt % branched C₅ alkanes if the hydrocarbon feed was the normal C₅ alkane or at least about 3 wt % normal C₅ alkanes if the hydrocarbon feed was the branched C₅ alkane in 1 hr based on the normal C₅ alkane or branched C₅ alkane in the hydrocarbon feed, the reaction mixture having a Reid vapor pressure in a range of about 1 to about 25 and an octane number in a range of about 50 to about
 110. 